Various systems and facilities intake large quantities of water from various exposed natural and other above-ground water sources, such as rivers, lakes, oceans, reservoirs, irrigation and flood water canals, outdoor water parks, other water conveyance structures, and the like. Examples of such systems and facilities include hydroelectric plants, pulp and paper mills, steel mills, petro-chemical plants, municipal water systems and waste water plants, nuclear and other energy facilities that use the water for cooling or for other purposes, other water filtering or screening facilities, etc. In all such systems it is important to screen naturally occurring debris found in the exposed above-ground water source from the flow of water that is taken into and employed by the system or facility. Such debris may include, for example, leaves, branches, and other portions of trees or other plants that have fallen into or grown in the water source, trash, and other debris that has been dumped or otherwise found its way into the exposed above-ground water source, etc. Such debris could cause significant damage to the system or facility obtaining water from the exposed above-ground water source if it were allowed to enter into the system or facility.
Various screening systems are known and used for preventing debris found in exposed above-ground water sources from entering into the systems or facilities described above. For example, fine mesh screening may be used to exclude even small pieces of debris from such systems. Screening systems with larger openings may be used, either alone or in combination with finer screening, to prevent large debris from entering the system or facility taking water from the exposed above-ground water source. Such larger opening screening systems may be used for preventing large debris from reaching finer mesh screening positioned downstream from the larger opening screening. Larger opening screening systems preferably do not dramatically adversely affect the water flow volume provided into the facility or system through the screening system.
An exemplary screening system of this type is known as an intake rack system or trash rack. Intake rack systems typically provide screening using a series of vertically oriented parallel blades separated by spacers and mounted on horizontally oriented rods. The spacing between the blades forming the intake rack is selected to screen debris of the desired size from entering the water intake of the system or facility that the trash rack is protecting, without significantly reducing water flow into the water intake. Such intake racks may be made of metallic or non-metallic materials. Intake racks of this type are available, for example, from Hydro Component Systems, LLC of Watertown, Wis. In a typical application, intake racks of this type may be mounted upstream from the water intake of a hydroelectric or other plant, system or facility that intakes water from a river or other similar exposed above-ground water source. The elongated vertically oriented parallel blades forming the intake rack extend downward into the water to prevent debris floating at the water surface or in the water below the water line from entering the system or facility.
As an intake rack or other screening structure prevents the flow of debris into the water intake of a system or facility from an exposed above-ground water source, the debris being screened will build up on the intake rack or other screening structure. This accumulating debris must be cleared from the intake rack or other screening structure on a regular basis, to prevent the buildup of such debris from interfering with the flow of water into the system or facility water intake. One way to remove such accumulated debris from an intake rack or other screening structure is to remove the rack or other screening structure from its operational position for cleaning. Removing an intake rack or other screening structure for cleaning, however, is not a practical solution in many applications. For example, where an intake rack is used to screen debris from a water intake positioned on a river, debris flowing down the river can accumulate on the intake rack so rapidly as to require cleaning thereof on, in some cases, a daily basis, or even more often. Furthermore, removing an intake rack or other screening structure from service can require shutting down the system for which the structure is providing screening, or the use of a more complicated and expensive redundant screening system. Thus, various tools have been developed for cleaning accumulated debris from intake racks and similar screening systems without removing the racks from operation.
A typical tool for removing accumulated debris from an intake rack is known as a trash rake. A typical trash rake can include a rake-like structure including tines that are spaced apart so as to fit between the blades of an intake rack to be cleaned. This rake-like structure is positioned adjacent to and drawn vertically along the intake rack blades to remove accumulated debris therefrom.
Although trash rakes of this type may be operated manually, powered trash rake systems also have been developed that use powered systems to position a trash rake adjacent to the intake rack to be cleaned to break up accumulated debris and to draw the trash rake vertically along the intake rack to remove the debris therefrom. Typically, such powered trash rake systems have employed hydraulic mechanisms to position and move the trash rake along the intake rack to be cleaned. The use of such hydraulic systems is problematic for several reasons. Since such systems often are used to clear intake racks associated with water intakes positioned in natural public water sources, pollution of the water source due to leaks of hydraulic fluid is a significant concern. Furthermore, in cold operating conditions, the hydraulic fluid used in such systems can become fixed or viscous, such that powered trash rakes using such hydraulic systems do not work well in cold operating conditions.
Another limitation of existing powered trash rake systems, whether using hydraulic or other powered operation, is that such systems are not fully powered in all phases of operation. For example, current powered trash rake systems often rely on gravity to lower a trash rake structure into position along the intake rack to be cleared. An electric motor may then be used only to draw the trash rake structure upward along the intake rack, to clear debris therefrom. Relying on gravity and the weight of the trash rake structure to position the trash rake structure in the downward direction can be a serious limitation of current trash rake systems. Such systems are limited in their ability to break up debris or ice accumulated at the intake rack or water surface. The debris cleared from the intake rack using such systems typically is dumped onto a deck or conveyor located at the top of the intake rack system to be hauled away to a nearby debris disposal location. Thus, an expensive and/or time consuming secondary system or process must be employed to haul away the debris that has been removed from an intake rack using such current systems. Current trash rake systems do not allow an operator under all operating conditions simply, easily, and effectively under full power to position a trash rake adjacent to an intake rack to be cleaned, to move the trash rake vertically across the rack effectively to remove debris therefrom, and then to carry the removed debris to a desired disposal location adjacent to the intake rack without the use of a secondary system or process.
What is desired, therefore, is a fully powered trash rake system for clearing debris from intake racks and similar water intake screening systems. Preferably, such a powered trash rake system may be manually or fully automatically controlled, does not employ any hydraulic systems that may cause pollution through leaks of hydraulic fluid, and is fully and effectively operable in all phases of operation in any weather, temperature, or other operating conditions.